Fri·Nov 12, 2021Friday·November 12, 2021

1. 01*

   Test of Nuclear Decay Rate Variation due to an Antineutrino Flux

   Shih-Chieh Liu (1)🇺🇸 · David Koltick (1) · Haoyu Wang (1)🇺🇸 · Jonathan Nistor (2)🇺🇸 · Jordan Heim (2)🇺🇸 · Thomas Ward (2) ((1) Department of Physics and Astronomy, Purdue University (2) TechSource Inc, Los Alamos)🇺🇸

   Unexplained variations of the decay rate for weak interaction decays such as ${\beta }^{\pm }$-decay, electron capture, as well as strong interaction $\alpha$-decay have been reported. Some researcher interpreted these variations as caused by an unexplained fundamental interaction. The purpose of the paper is to review decay rate parameter variations experiments and place them into a common comparable context and to make decay parameter measurements at the level of 10${}^{-5}$ in the presences of an antineutrino flux, $\sim 3\times 10^{12}$ $\overline{\nu }c{m}^{-2}se{c}^{-1}$, 6.5 meters from the High Flux Isotope Reactor(HFIR) reactor core having an on-off cycle time of $\sim$30 days. Two weak interaction decays, one via electron capture and the other via ${\beta }^{-}$ decay were selected because the final state and the time reverse state each contain a neutrino and anti-neutrino, covering arguments that the anti-neutrino flux may interact differently or not at all in one of the cases. The experiment searched for variation of the ${}_{25}^{54}$Mn, e${}^{-}$ capture and ${}_{55}^{137}$Cs, ${\beta }^{-}$ decay rate parameters. The measured variation in the decay rate parameters are found to be $\delta \lambda /\lambda =(0.034\pm 1.38)\times 10^{-5}$ for ${}_{25}^{54}$Mn and $\delta \lambda /\lambda =(0.67\pm 1.56)\times 10^{-5}$ for ${}_{55}^{137}$Cs. These results are consistent with no measurable decay rate parameter variation due to an antineutrino flux, yielding a $68\%$ confidence level upper limit sensitivity for ${}_{25}^{54}$Mn, $\delta \lambda /\lambda \le 1.31\times 10^{-5}$ or $\sigma \le 1.29\times 10^{-25}c{m}^2$ in cross section and for ${}_{55}^{137}$Cs, $\delta \lambda /\lambda \le 2.23\times 10^{-5}$ or $\sigma \le 5.69\times 10^{-27}c{m}^2$. These null or no observable effect measurements places cross-section upper limits $\sim 10^4$ times more sensitive than past experiments.

   nucl-exPRC(2022)·0 citations
2. 02*

   Characterizing the initial conditions of heavy-ion collisions at the LHC with mean transverse momentum and anisotropic flow correlations

   ALICE Collaboration

   Correlations between mean transverse momentum $[p_{\mathrm{T}}]$ and anisotropic flow coefficients $v_2$ or $v_3$ are measured as a function of centrality in Pb$-$Pb and Xe$-$Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and 5.44 TeV, respectively, with ALICE. In addition, the recently proposed higher-order correlation between $[p_{\mathrm{T}}]$, $v_2$, and $v_3$ is measured for the first time, which shows an anticorrelation for the presented centrality ranges. These measurements are compared with hydrodynamic calculations using IP-Glasma and ${\mathrm{T}}_{\mathrm{R}}\mathrm{ENTo}$ initial-state shapes, the former based on the Color Glass Condensate effective theory with gluon saturation, and the latter a parameterized model with nucleons as the relevant degrees of freedom. The data are better described by the IP-Glasma rather than the ${\mathrm{T}}_{\mathrm{R}}\mathrm{ENTo}$ based calculations. In particular, Trajectum and JETSCAPE predictions, both based on the ${\mathrm{T}}_{\mathrm{R}}\mathrm{ENTo}$ initial state model but with different parameter settings, fail to describe the measurements. As the correlations between $[p_{\mathrm{T}}]$ and $v_{\mathrm{n}}$ are mainly driven by the correlations of the size and the shape of the system in the initial state, these new studies pave a novel way to characterize the initial state and help pin down the uncertainty of the extracted properties of the quark$-$gluon plasma recreated in relativistic heavy-ion collisions.

   nucl-exhep-exPLB(2022)·79 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.